A vibrating cantilever footfall energy harvesting device

Gilbert, James M; Balouchi, Farouk

Abstract

Human footfall is an attractive source of energy for harvesting for low-power applications. However, the nature of footfall is poorly matched to electromagnetic generators. Footfall motion is characterised by high forces and low speeds, while electromagnetic generators are normally most efficient at relatively high speed. This article proposes a novel mechanism for converting the low-speed motion of footfall to a higher speed oscillating motion suitable for electromagnetic power generation. The conversion is achieved using a cantilever beam which is deflected by the footfall motion using a special ‘striker’ mechanism which then allows the cantilever to oscillate freely at a relatively high speed. An arrangement of permanent magnets attached to the cantilever causes an alternating magnetic field, and a stationary coil converts this to a usable voltage. This article describes the mechanism and provides a mathematical model of its behaviour which allows the system parameters to be optimised and its performance predicted. The performance of a prototype device is presented, and it is shown that this is capable of generating up to 60 mJ/step and that the conversion efficiency is up to 55%.

Citation

Gilbert, J. M., & Balouchi, F. (2014). A vibrating cantilever footfall energy harvesting device. Journal of Intelligent Material Systems and Structures, 25(14), 1738-1745. https://doi.org/10.1177/1045389X14521880

• Journal Article Type: Article
• Acceptance Date: Jan 3, 2014
• Online Publication Date: Feb 6, 2014
• Publication Date: 2014-09
• Deposit Date: Feb 24, 2016
• Publicly Available Date: Feb 24, 2016
• Journal: Journal of intelligent material systems and structures
• Print ISSN: 1045-389X
• Publisher: SAGE Publications
• Peer Reviewed: Peer Reviewed
• Volume: 25
• Issue: 14
• Pages: 1738-1745
• DOI: https://doi.org/10.1177/1045389X14521880
• Keywords: Energy harvesting, Energy scavenging, Footfall, Efficiency, Energy conversion
• Public URL: https://hull-repository.worktribe.com/output/411371
• Publisher URL: http://jim.sagepub.com/content/25/14/1738
• Additional Information: This is an author's accepted manuscript of an article published in Journal of intelligent material systems and structures, 2014, v.25 issue 14
• Contract Date: Feb 24, 2016